Polyphenylene ether, method for manufacturing polyphenylene ether, porous film, pharmaceutical process filter, and water treatment film

Abstract

The purpose of the present invention is to provide a polyphenylene ether having a low proportion of low-molecular-weight components and excellent solubility in water-soluble organic solvents, and a method for manufacturing the same.　In order to solve the problems described above, the present invention is characterized in that, with respect to a total of 100 mol% of repeating units represented by formula (1) below and formula (2) below, the content of repeating units derived from phenol represented by formula (1) below is 70 mol% to 99.5 mol% and the content of repeating units derived from phenol represented by formula (2) below is 0.5 mol% to 30 mol%, and a polyphenylene ether component having a molecular weight of 1.0x104 or less as determined by gel permeation chromatography (GPC) is 15 wt% or less.

Description

Polyphenylene ether, method for producing polyphenylene ether, porous membrane, pharmaceutical process filter, and water treatment membrane

[0001] This invention relates to polyphenylene ether, a method for producing the same, a porous membrane, a diaphragm for alkaline electrolysis, a process filter for pharmaceuticals, and a water treatment membrane.

[0002] Polyphenylene ethers (hereinafter also referred to as "PPE") are widely used as materials for products and components in the electrical and electronic, automotive, and food and packaging fields, as well as in various other industrial materials, due to their excellent high-frequency properties, flame retardancy, and heat resistance. Generally, polyphenylene ethers having repeating units derived from monovalent phenols, such as 2,6-dimethylphenol, are soluble in solvents such as chloroform, but have the problem of being insoluble at room temperature (20°C) in water-soluble organic solvents such as N-methyl-2-pyrrolidone. Therefore, when used as a material for porous membranes produced by methods such as non-solvent-induced phase separation, handling them in solution during manufacturing is difficult.

[0003] Furthermore, Patent Document 1 discloses polyphenylene ether copolymers, such as polyphenylene ether copolymerized with 2,6-dimethylphenol and 2-tert-butyl-5-methylphenol. It discloses that polyphenylene ether copolymers with relatively high molecular weights can be polymerized with the aim of improving the mechanical properties of molded articles produced by injection molding and press molding. However, the possibility of application to porous films and solubility in water-soluble organic solvents are not suggested, and furthermore, since higher toughness than conventional molded articles is required for application to films, the conventional polymerization technology of polyphenylene ethers disclosed has been problematic because a large amount of low molecular weight components remain, which is a unique issue when copolymerizing two types of phenols, and as a result the mechanical properties for application to films are insufficient.

[0004] Japanese Unexamined Patent Publication No. 56-104935

[0005] As described above, regarding the conventionally disclosed technologies, polyphenylene ethers that are excellent in solubility in water-soluble organic solvents, capable of forming porous membranes at room temperature, and have a small ratio of low molecular weight components have not been obtained, and the development of a technology capable of obtaining such polyphenylene ethers is desired.

[0006] Therefore, an object of the present invention is to provide a polyphenylene ether having a small ratio of low molecular weight components and excellent solubility in water-soluble organic solvents, and a method for producing the polyphenylene ether. Another object of the present invention is to provide a porous membrane having improved mechanical properties, produced using the polyphenylene ether of the present invention, and an alkali electrolysis diaphragm, a pharmaceutical process filter, and a water treatment membrane using such a porous membrane.

[0007] As a result of intensive studies to solve the above problems, the present inventors have found that by reducing the ratio of low molecular weight components having a molecular weight of 10,000 or less in a polyphenylene ether copolymer to a specific amount, the solubility in water-soluble organic solvents is excellent, and Further, the present inventors have clarified that by using a specific solvent as a poor solvent added in the precipitation step during production, it is possible to provide a polyphenylene ether copolymer having a reduced ratio of low molecular weight components having a molecular weight of 10,000 or less.

[0008] That is, the present invention is as follows. [1] With respect to a total of 100 mol% of the repeating units of the following formula (1) and the following formula (2), the content of the repeating unit derived from the phenol of the following formula (1) is 70 mol% or more and 99.5 mol% or less, and the content of the repeating unit derived from the phenol of the following formula (2) is 0.5 mol% or more and 30 mol% or less, and the molecular weight determined by gel permeation chromatography (GPC) is 1.0 × 10 ４ A polyphenylene ether, characterized in that the following polyphenylene ether component is 15% by weight or less. (In formula (1), R 11is, independently of each other, an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, R 12 is, independently of each other, a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.) (In formula (2), R 22 is, independently of each other, a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and two Rs 22 are not both hydrogen atoms, and R 21 is a partial structure represented by the following formula (3). (In formula (3), R 31 is, independently of each other, an optionally substituted linear alkyl group having 1 to 8 carbon atoms, or a cyclic alkyl structure having 1 to 8 carbon atoms to which two Rs 31 are bonded, and R 32 is, independently of each other, an optionally substituted alkylene group having 1 to 8 carbon atoms, b is, independently of each other, 0 or 1, and R 33 is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms or an optionally substituted phenyl group.)) [2] The polyphenylene ether according to [1], wherein the partial structure represented by the formula (3) is a t-butyl group. [3] The weight average molecular weight (Mw) determined by gel permeation chromatography (GPC) is 7.0 × 10 ４ or more. The polyphenylene ether according to [1] or [2]. [4] The polyphenylene ether according to any one of [1] to [3], wherein the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography (GPC) is 2.0 to 5.0. [5] The polyphenylene ether according to any one of [1] to [4], wherein the polyphenylene ether component having a molecular weight of 5.0 × 10 ３ or less is 8.0% by weight or less. [6] The polyphenylene ether according to any one of [1] to [4], wherein the polyphenylene ether component having a molecular weight of 5.0 × 10５ The polyphenylene ether according to any one of [1] to [5], characterized in that the above polyphenylene ether component is 20% by weight or less. [7] A method for producing the polyphenylene ether according to any one of [1] to [6], comprising a polymerization step of polymerizing a phenol compound to obtain a crude polymer, and a precipitation step of mixing the crude polymer with a precipitation solvent to precipitate polyphenylene ether, wherein the precipitation solvent contains a first solvent and a second solvent, and the solubility parameter (SP value) (unit (cal / cm ３ )) of the second solvent is 9.0 or more and 12.0 or less. A method for producing polyphenylene ether. [8] The method for producing polyphenylene ether according to [7], characterized in that the first solvent is an alcohol having 1 to 3 carbon atoms. [9] The method for producing polyphenylene ether according to [7] or [8], characterized in that the second solvent is an alcohol, ketone, ester, amide or lactam having 4 to 8 carbon atoms.

[10] The method for producing polyphenylene ether according to [7] or [8], characterized in that the second solvent is an alcohol having 4 to 8 carbon atoms, acetone, methyl ethyl ketone or N-methyl-2-pyrrolidone.

[11] The method for producing polyphenylene ether according to any one of [7] to

[10] , characterized in that the mass ratio of the first solvent to the second solvent is 10:90 to 49:51.

[12] The method for producing polyphenylene ether according to any one of [7] to

[11] , characterized in that the first solvent is methanol and the second solvent is methyl ethyl ketone.

[13] A porous membrane comprising the polyphenylene ether according to any one of [1] to [6].

[14] A pharmaceutical process filter comprising the porous membrane according to

[13] .

[15] A water treatment membrane comprising the porous membrane according to

[13] .

[0009] ​​According to the present invention, it is possible to provide a polyphenylene ether with a low molecular weight component ratio and excellent solubility in water-soluble organic solvents, and a method for producing the same. Furthermore, according to the present invention, it is possible to provide a porous membrane with improved mechanical properties made using the above polyphenylene ether, and a diaphragm for alkaline electrolysis, a process filter for pharmaceuticals, and a water treatment membrane using such a porous membrane.

[0010] The present invention will be described in detail below based on its embodiments.

[0011] <Explanation of Terms> In this specification, "hydrocarbon group" includes "aliphatic hydrocarbon group" and "aromatic hydrocarbon group". "Aliphatic hydrocarbon group" includes "chain hydrocarbon group" and "alicyclic hydrocarbon group". From another perspective, "aliphatic hydrocarbon group" includes "saturated hydrocarbon group" and "unsaturated hydrocarbon group". In this specification, "saturated hydrocarbon group" includes, for example, chain hydrocarbon groups such as methyl group, ethyl group, propyl group, n-butyl group, isopropyl group, isobutyl group, 1-methylpentyl group, 1-ethylpentyl group, sec-butyl group, and tert-butyl group as monovalent saturated hydrocarbon groups; and alicyclic hydrocarbon groups such as cyclopropyl group and cyclobutyl group. In this specification, "unsaturated hydrocarbon group" refers to a linear or branched hydrocarbon group having 2 to 6 carbon atoms and containing at least one carbon-carbon double or triple bond. Specifically, examples include vinyl group, allyl group, methyl vinyl group, propenyl group, butenyl group, pentenyl group, hexenyl group, ethynyl group, 2-propynyl group, etc. In this specification, "aryl group" refers to a monovalent aromatic hydrocarbon group, which may be monocyclic or polycyclic, and has 6 to 20 carbon atoms. Examples include phenyl group, 1-naphthyl group, 2-naphthyl group, anthryl group, phenanthryl group, pyrenyl group, indenyl group, or indanyl group. In this specification, "alkyl group" may be a linear, branched, or cyclic alkyl group, and examples include a methyl group, ethyl group, propyl group, isopropyl group, n-butyl group, isobutyl group, sec-butyl group, tert-butyl group, n-pentyl group, isopentyl group, tert-pentyl group, neopentyl group, 1,2-dimethylpropyl group, n-hexyl group, isohexyl group, (n-)heptyl group, (n-)octyl group, (n-)nonyl group, (n-)decyl group, (n-)undecyl group, (n-)dodecyl group, cyclopropyl group, cyclobutyl group, cyclopentyl group, cyclohexyl group, cycloheptyl group, cyclooctyl group, or cyclononyl group. In this specification, "alkylene group" may be a divalent group obtained by removing one arbitrary hydrogen atom from the "alkyl group". Examples of "halogen atoms" include fluorine atoms, chlorine atoms, bromine atoms, and iodine atoms.In this specification, a water-soluble organic solvent is an organic solvent whose solubility in water at 20°C is 50 g / 100 mL or more. Specific examples of water-soluble organic solvents include N-methyl-2-pyrrolidone, N,N-dimethylacetamide, dimethyl sulfoxide, N,N-dimethylformamide, and γ-butyrolactone.

[0012] (Polyphenylene ether) The polyphenylene ether of this embodiment consists of repeating units derived from phenol represented by the following formula (1) and repeating units derived from phenol represented by the following formula (2), wherein the content of repeating units derived from phenol of formula (1) is 70 mol% or more and 99.5 mol% or less, and the content of repeating units derived from phenol of formula (2) is 0.5 mol% or more and 30 mol or less, based on 100 mol% of the total of each repeating unit. By including the repeating units derived from phenol represented by the following formulas (1) and (2) in the above proportions, the polyphenylene ether has excellent solubility in water-soluble organic solvents, and the mechanical properties of the resulting porous membrane tend to improve. (In formula (1), R 11 Each of these is independently a saturated hydrocarbon group having 1 to 6 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, R 12 Each of these is independently a hydrogen atom, an optionally substituted C1-C6 hydrocarbon group, an optionally substituted C6-C12 aryl group, or a halogen atom. (In formula (2), R 22 Each of these is independently a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms which may be substituted, an aryl group having 6 to 12 carbon atoms which may be substituted, or a halogen atom, and two R 22 Both are not hydrogen atoms, R 21 This is a substructure represented by the following formula (3). (In formula (3), R 31 Each of these is independently a linear alkyl group having 1 to 8 carbon atoms, which may be substituted, or two R 31It is a cyclic alkyl structure with 1 to 8 carbon atoms bonded together, R 32 Each is independently an alkylene group having 1 to 8 carbon atoms, which may be substituted, and each is independently 0 or 1, R 33 )) From a similar viewpoint, the polyphenylene ether preferably contains, with respect to 100 mol% of the total repeating units of formula (1) and formula (2), the content of the repeating units derived from phenol of formula (1) is 80 mol% or more and 97 mol% or less, the content of the repeating units derived from phenol of formula (2) is 3 mol% or more and 20 mol% or less, the content of the repeating units derived from phenol of formula (1) is 85 mol% or more and 95 mol% or less, the content of the repeating units derived from phenol of formula (2) is 5 mol% or more and 15 mol% or less, the content of the repeating units derived from phenol of formula (1) is 90 mol% or more and 95 mol% or less, the content of the repeating units derived from phenol of formula (2) is 5 mol% or more and 10 mol% or less.

[0013] In the above formula (1), R 11 Each of these is preferably an independently saturated hydrocarbon group having 1 to 6 carbon atoms or an aryl group having 6 to 12 carbon atoms, more preferably a methyl group or a phenyl group, and even more preferably a methyl group. In formula (1), the two R 11 It is preferable that both have the same structure.

[0014] In the above formula (1), R 12 Each of these is preferably a hydrogen atom or a hydrocarbon group having 1 to 6 carbon atoms, and more preferably a hydrogen atom or a methyl group. In formula (1), the two R 12 These are preferably different, and more preferably one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group).

[0015] In the above formula (2), R 22Each of these is preferably independently a hydrogen atom, a saturated or unsaturated hydrocarbon group having 1 to 15 carbon atoms, or an aryl group having 6 to 12 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; more preferably a hydrogen atom, a hydrocarbon group having 1 to 6 carbon atoms, or an aryl group having 6 to 10 carbon atoms that may be substituted with an alkyl group having 1 to 6 carbon atoms; and even more preferably a hydrogen atom or a methyl group. In formula (2), the two R 22 These are preferably different, and more preferably one is a hydrogen atom and the other is a hydrocarbon group having 1 to 6 carbon atoms (preferably a methyl group).

[0016] The substructure represented by formula (3) above is preferably a group containing secondary and / or tertiary carbons, such as an isopropyl group, isobutyl group, sec-butyl group, tert-butyl group, tert-amyl group, 2,2-dimethylpropyl group, cyclohexyl group, or a structure having a phenyl group at its terminal, more preferably a tert-butyl group or a cyclohexyl group, and even more preferably a tert-butyl group.

[0017] In this embodiment, the structure of the polyphenylene ether can be identified by analyzing it using methods such as NMR and mass spectrometry. Specific methods for identifying the structure of the polyphenylene ether include performing field desorption mass spectrometry (FD-MS), which is known to be less prone to fragmentation, and estimating the repeating units based on the spacing of the detected ions. Furthermore, a method for estimating the structure of the polyphenylene ether can be used, which involves combining electron ionization (EI) peak analysis of fragment ions with structural analysis by NMR.

[0018] Since the phenol in formula (1) above does not have an unsubstituted ortho position (i.e., hydrogen atoms are not bonded to the two ortho carbon atoms of the carbon atom to which the hydroxyl group is bonded), it can react with other phenolic monomers only at the phenolic hydroxyl group and the para carbon atom. Therefore, the repeating unit derived from formula (1) above includes a repeating unit having the structure of formula (4) below. (In formula (4), R 11 and R12 This is the same as equation (1).

[0019] The phenol of formula (2) can react with another phenolic monomer at either the ortho or para position of the phenol, in addition to the phenolic hydroxyl group. Therefore, the repeating units derived from the phenol of formula (2) have the structures of formula (5), formula (6), or combinations thereof. (R in equations (5) and (6)) 21 , R 22 This is the same as equation (2).

[0020] Furthermore, the polyphenylene ether may contain structural units derived from phenol of the following formula (7). (In equation (7), X is any a-valent linking group, a is an integer from 2 to 6, R 4 (This is either a linear alkyl group having 1 to 8 carbon atoms or a substructure represented by formula (3), and is bonded to at least one of the carbon atoms at positions 2 or 6 of the benzene ring to which -O- is bonded, with the carbon atom at position 1 being the bonded position, and k is an integer from 1 to 4, independently of each other.)

[0021] In the above formula (7), R 4 Each of these is independently one of a linear alkyl group having 1 to 8 carbon atoms, such as a methyl group, an ethyl group, or an n-propyl group, and one of the substructures represented by formula (3) above, and it is preferable that each is a methyl group or one of the substructures represented by formula (3) above. Each of the a substructures may have the same structure or may be different. In particular, from the viewpoint of having even better solubility in water-soluble organic solvents, it is preferable that each of the a substructures has the same structure.

[0022] In the above formula (7), k is an integer from 1 to 4, and preferably an integer from 2 to 4.

[0023] In the above formula (7), R 4 The R bonded to the benzene ring is positioned at position 2 and at least one of the carbon atoms at positions 2 and 6, with the carbon atom to which the -O- bond is attached being at position 1. 4When is a linear alkyl group having 1 to 8 carbon atoms, it is preferable that it is bonded to both the 2nd and 6th positions, and R bonded to the 2nd and / or 6th positions 4 When the substructure is represented by formula (3), it is preferable that it is bonded to only one of either the 2nd or 6th position.

[0024] The polyphenylene ether of this embodiment may also include repeating units derived from the phenol represented by formula (7), repeating units derived from the phenol represented by formula (1), and repeating units derived from the phenol represented by formula (2). In this case, R of formula (2) 21 and R in the above equation (7) 4 If both are substructures (functional groups) represented by formula (3) (i.e., both the phenol compound represented by formula (2) and the phenol compound represented by formula (7) are substituted with the substructures (functional groups) represented by formula (3)), the structures of each substructure (functional group) represented by formula (3) may be the same or different.

[0025] When the repeating units derived from the phenol represented by formula (7) are included, as well as the repeating units derived from the phenol represented by formula (1) and the repeating units derived from the phenol represented by formula (2), the proportion of these repeating units is preferably such that, based on 100 mol% of the total of the repeating units derived from the phenol represented by formula (1), the repeating units derived from the phenol represented by formula (2), and the repeating units derived from the phenol represented by formula (7), the repeating units consist of 50 to 100 mol% of the repeating units derived from the phenol represented by formula (1), 0 to 30 mol% of the repeating units derived from the phenol represented by formula (2), and 0 to 40 mol% of the repeating units derived from the phenol represented by formula (7).

[0026] In formula (7) above, X is any a-valent linking group and is not particularly limited, but examples include hydrocarbon groups such as chain hydrocarbon groups and cyclic hydrocarbon groups; hydrocarbon groups containing one or more atoms selected from nitrogen, phosphorus, silicon, and oxygen; atoms such as nitrogen, phosphorus, and silicon; or groups combining these. X may be a linking group excluding single bonds. X may be a linking group that links a substructures together.

[0027] As for X above, R is connected via a single bond or an ester bond, etc. 4 R 4 R 4 Examples include α-valent heterocyclic skeletons bonded to a benzene ring.

[0028] Here, the alkyl skeleton is not particularly limited, but examples include a linear hydrocarbon (e.g., a linear saturated hydrocarbon) with at least a number of carbon atoms (2 to 6) whose branched ends are directly bonded to a benzene ring of the substructure (it is sufficient that a benzene ring is bonded to a branched end, and there may be branched ends that are not bonded to a benzene ring). Also, the aryl skeleton is not particularly limited, but examples include a benzene ring, a mesitylene group, or a 2-hydroxy-5-methyl-1,3-phenylene group bonded via a single bond or an alkyl chain, R 4 Examples include skeletons that bond to a benzene ring to which R is attached. Furthermore, there are no particular limitations on the heterocyclic skeleton, but for example, a triazine ring is bonded via a single bond or alkyl chain, 4 Examples include skeletons that bond to the benzene ring to which the compound is attached.

[0029] In the above formula (7), a is an integer between 2 and 6, preferably between 2 and 4.

[0030] If the phenol represented by formula (7) does not have an unsubstituted ortho position, the structural unit derived from the phenol represented by formula (7) has the structure represented by formula (8) below, and if the phenol represented by formula (7) has an unsubstituted ortho position, the structural unit derived from the phenol of formula (7) has the structure represented by formula (8) below, the structure represented by formula (9) below, or a combination thereof. (R in equations (8) and (9)) 4 This is the same as equation (7).

[0031] Furthermore, the number-average molecular weight (Mn) of the polyphenylene ether in this embodiment is preferably 10,000 or more and 400,000 or less. When the number-average molecular weight is within this range, it is soluble in water-soluble organic solvents used in film formation, and at the same time, the film strength as a porous film tends to be high. The lower limit of the number-average molecular weight (Mn) is more preferably 15,000 or more, even more preferably 17,000 or more, particularly preferably 20,000 or more, and most preferably 25,000 or more. If the number-average molecular weight (Mn) is 10,000 or more, the resulting porous film has excellent handling properties, and if it is 20,000 or more, the film strength is sufficient. The upper limit of the number-average molecular weight (Mn) is more preferably 200,000 or less. When the number-average molecular weight (Mn) is 200,000 or less, it has excellent solubility in water-soluble organic solvents and excellent handling properties of the solution during film formation.

[0032] Furthermore, the weight-average molecular weight (Mw) of the polyphenylene ether in this embodiment is preferably 50,000 or more and 1,000,000 or less. If the weight-average molecular weight (Mw) is below this upper limit, it is soluble in water-soluble organic solvents used in film formation, and at the same time, the film strength as a porous film tends to be high. The lower limit of the weight-average molecular weight is more preferably 60,000 or more, even more preferably 70,000 or more, even more preferably 80,000 or more, and most preferably 100,000 or more. If the weight-average molecular weight (Mw) is 50,000 or more, the resulting porous film has excellent handling properties, and if it is 70,000 or more, the film strength is sufficient. The upper limit of the weight-average molecular weight (Mw) is more preferably 500,000 or less, even more preferably 300,000 or less, and even more preferably 150,000 or less. If the weight-average molecular weight (Mw) is 500,000 or less, it exhibits excellent solubility in water-soluble organic solvents and offers excellent handling of the solution during film formation.

[0033] The molecular weight distribution (weight-average molecular weight / number-average molecular weight (Mw / Mn)) of the polyphenylene ether in this embodiment is, for example, 2.0 or more and 6.0 or less. When the molecular weight distribution is 2.0 or more and 6.0 or less, when a porous film is formed using the polyphenylene ether solution, there is a tendency for an excellent balance between improved mechanical properties of the porous film and ease of handling of the solution during film formation. The upper limit of the molecular weight distribution is more preferably 5.0 or less, and even more preferably 4.5 or less.

[0034] Furthermore, the polyphenylene ether of this embodiment has a molecular weight of 1.0 × 10 ４ The content ratio of the following polyphenylene ether component is 15.0% by weight or less. Molecular weight 1.0 × 10 ４ By keeping the content ratio of the following polyphenylene ether components low, there is a tendency to improve the mechanical properties of porous films when porous films are fabricated using polyphenylene ether. For the same reason, molecular weight 1.0 × 10 ４The content ratio of the following polyphenylene ether components is more preferably 12.0% by weight or less, even more preferably 10.0% by weight or less, particularly preferably 8.0% by weight or less, and most preferably 4.0% by weight or less.

[0035] Furthermore, the polyphenylene ether of this embodiment has a molecular weight of 5.0 × 10 ３ It is preferable that the content ratio of the following polyphenylene ether components is 8.0% by weight or less. In this case, when a porous film is formed using polyphenylene ether, the mechanical properties of the porous film tend to be further improved. For similar reasons, a molecular weight of 5.0 × 10⁻⁶ is preferable. ３ The content ratio of the following polyphenylene ether components is more preferably 5.5% by weight or less, even more preferably 4.5% by weight or less, particularly preferably 3.0% by weight or less, and most preferably 2.0% by weight or less.

[0036] Furthermore, the polyphenylene ether of this embodiment has a molecular weight of 5.0 × 10 ５ It is preferable that the content ratio of the above polyphenylene ether components is 20.0% by weight or less. In this case, the solution viscosity becomes appropriate when forming a porous film using polyphenylene ether, and in addition to being able to increase the porosity of the porous film, a homogeneous liquid free of insoluble components can be obtained. For similar reasons, a molecular weight of 5.0 × 10⁻⁶ is preferable. ５ The content ratio of the polyphenylene ether component is more preferably 16.0% by weight or less, even more preferably 10.0% by weight or less, particularly preferably 8.0% by weight or less, and most preferably 4.0% by weight or less.

[0037] The molecular weight, number-average molecular weight, and weight-average molecular weight of the polyphenylene ether in this embodiment described above were measured by gel permeation chromatography (GPC). Furthermore, the molecular weight mentioned above is 1.0 × 10⁻⁶. ４ The following polyphenylene ether components have a content ratio and molecular weight of 5.0 × 10 ３The following polyphenylene ether content ratios are calculated from the ratio of areas below each molecular weight, with the total area enclosed by the differential molecular weight distribution curve obtained by GPC set to 100%. Similarly, molecular weight 5.0 × 10 ５ The above polyphenylene ether content ratio is calculated by taking the total area enclosed by the differential molecular weight distribution curve obtained by GPC as 100%, with a molecular weight of 5.0 × 10⁻⁶. ５ This value was calculated from the area ratios mentioned above.

[0038] (Method for producing polyphenylene ether) The polyphenylene ether of this embodiment can be obtained by a production method comprising: a polymerization step of polymerizing a phenol compound in a good solvent for polyphenylene ether to obtain a polymer solution; and a precipitation step of adding the polymer solution and a poor solvent for polyphenylene ether to a precipitation tank to precipitate the polyphenylene ether. Polymerization step The polyphenylene ether can be obtained by a method that includes at least a step of oxidative polymerization of a monovalent phenol compound represented by formula (1) or formula (2), or oxidative polymerization of monovalent and polyvalent phenol compounds represented by formula (1) or formula (7). The step of oxidative polymerization preferably involves oxidative polymerization of a raw material containing at least the phenol of formula (1) and the phenol of formula (2), or the phenol of formula (1) and the phenol of formula (7).

[0039] Examples of monovalent phenol compounds represented by the above formula (1) include 2,6-dimethylphenol, 2-methyl-6-ethylphenol, 2,6-diethylphenol, 2-ethyl-6-n-propylphenol, 2-methyl-6-chlorophenol, 2-methyl-6-bromophenol, 2-methyl-6-n-propylphenol, 2-ethyl-6-bromophenol, 2-methyl-6-n-butylphenol, 2,6-di-n-propylphenol, 2-ethyl-6-chlorophenol, 2-methyl-6-phenylphenol, 2,6-diphenylphenol, 2-methyl-6-tolylphenol, 2,6-ditolylphenol, 2,3,6-trimethylphenol, 2,3-diethyl-6-n-propylphenol, 2,3,6-tributylphenol, 2,6-di-n-butyl-3-methylphenol, 2,6-dimethyl-3-n-butylphenol, and 2,6-dimethyl-3-t-butylphenol. In particular, 2,6-dimethylphenol, 2,3,6-trimethylphenol, and 2,6-diphenylphenol are preferred because they are inexpensive and readily available. The monovalent phenol compound represented by formula (1) above may be used individually or in combination of multiple types.

[0040] Examples of monovalent phenol compounds represented by formula (2) above include 2-isopropyl-5-methylphenol, 2-cyclohexyl-5-methylphenol, 2-tert-butyl-5-methylphenol, and 2-isobutyl-5-methylphenol. From the viewpoint of suppressing multi-branching and gelation, 2-t-butyl-5-methylphenol and 2-cyclohexyl-5-methylphenol, which have bulky substituents, are more preferred. One monovalent phenol compound represented by formula (2) above may be used alone, or multiple types may be used in combination.

[0041] Among the polyvalent phenol compounds represented by the above formula (7), examples of phenol compounds having two phenol units in the molecule include 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane, 2,2-bis(4-hydroxy-3-methylphenyl)propane, 4,4'-methylenebis(2,6-dimethylphenol), bis(4-hydroxy-3-methylphenyl)sulfide, bis(4-hydroxy-3,5-dimethylphenyl)sulfone, α,α'-bis(4-hydroxy-3,5-dimethylphenyl)-1,4-diisopropylbenzene, 9,9-bis(4-hydroxy-3-methylphenyl)fluorene, 1,1-bis(4-hydroxy-3-methylphenyl)cyclohexane, and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane. In particular, 2,2-bis(3,5-dimethyl-4-hydroxyphenyl)propane and 1,1-bis(2-methyl-4-hydroxy-5-t-butylphenyl)butane are preferred because they are inexpensive and readily available.

[0042] Furthermore, among the polyvalent phenol compounds represented by formula (7) above, phenol compounds having three or more phenol units in the molecule include, for example, 4,4'-[(3-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 4,4'-[(4-hydroxyphenyl)methylene]bis(2,6-dimethylphenol), and 4,4'-[(4-hydroxyphenyl)methylene]bis(2,3,6-trimethylphenol). 4,4'-[(2-hydroxy-3-methoxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(4-hydroxy-3-ethoxyphenyl)methylene]bis(2,3,6-trimethylethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,6-dimethylphenol), 4,4'-[(3,4-dihydroxyphenyl)methylene]bis(2,3,6-trimethylphenol), 2,2'-[(4-hydroxyphenyl)methylene]bis(3,5,6-trimethylethylphenol) Bis(2,6-dimethylphenol), 4,4'-[4-(4-hydroxyphenyl)cyclohexylidene]bis(2,6-dimethylphenol), 4,4'-[(2-hydroxyphenyl)methylene]-bis(2,3,6-trimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3,5-dimethylphenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6-dimethylphenol), 4,4'-[1-[4-[1-(4-hydroxy-3-fluorophenyl)-1-methylethyl]phenyl]ethylidene]bis(2,6 -dimethylphenol), 2,6-bis[(4-hydroxy-3,5-dimethylphenyl)ethyl]-4-methylphenol, 2,6-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-4-methylphenol, 2,6-bis[(4-hydroxy-3,5,6-trimethylphenyl)methyl]-4-ethylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-methylphenol, 2,6-bis[(4-hydroxy-3-methylphenyl)methyl]-4-methylphenol, 2,4-bis[(4-hydroxy-3-cyclohexylphenyl)methyl]-6-methylphenol, 2,4-bis[(4-hydroxy-3-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(2-hydroxy-5-methylphenyl)methyl]-6-cyclohexylphenol, 2,4-bis[(4-hydroxy-2,3,6-trimethylphenyl)methyl]-6-cyclohexylphenol, 3,6-bis[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2-benzenediol, 4,6-bis[(4-Hyd [(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6-tris[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,4,6-tris[(2-hydroxy-3,5-dimethylphenyl)methyl]-1,3-benzenediol, 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,5 / 3,6-dimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-3,5-dimethylphenyl)methyl]-4-methylphenol ], 2,2'-methylenebis[6-[(4 / 2-hydroxy-2,3,5 / 3,4,6-trimethylphenyl)methyl]-4-methylphenol], 2,2'-methylenebis[6-[(4-hydroxy-2,3,5-trimethylphenyl)methyl]-4-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-6-methylphenol], 4,4'-methylenebis[2-[(2,4-dihydroxyphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,4-dihydro [xy-3-methylphenyl)methyl]-3,6-dimethylphenol], 4,4'-methylenebis[2-[(2,3,4-trihydroxyphenyl)methyl]-3,6-dimethylphenol], 6,6'-methylenebis[4-[(4-hydroxy-3,5-dimethylphenyl)methyl]-1,2,3-benzenetriol], 4,4'-cyclohexylidenebis[2-cyclohexyl-6-[(2-hydroxy-5-methylphenyl)methyl]phenol], 4,4'-cyclohexylidenebis[2-cyclohexyl-6-[(4-hydroxy-3,Examples include 5-dimethylphenyl)methyl]phenol], 4,4'-cyclohexyllidenebis[2-cyclohexyl-6-[(4-hydroxy-2-methyl-5-cyclohexylphenyl)methyl]phenol], 4,4'-cyclohexyllidenebis[2-cyclohexyl-6-[(2,3,4-trihydroxyphenyl)methyl]phenol], 4,4',4'',4'''-(1,2-ethanediylidene)tetrakis(2,6-dimethylphenol), 4,4',4'',4'''-(1,4-phenylenedimethylidene)tetrakis(2,6-dimethylphenol), and 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane. Among these, 1,1,3-tris(2-methyl-4-hydroxy-5-t-butylphenyl)butane is particularly preferred because it is inexpensive and readily available. The polyvalent phenol compound represented by formula (7) above may be used individually or in combination of multiple types.

[0043] Typically, oxidative polymerization of phenols having a hydrogen atom in the ortho position (e.g., 2-methylphenol, 2,5-dimethylphenol, 2-phenylphenol) can result in the formation of ether bonds even at the ortho position. This makes it difficult to control the bonding position of the phenol compound during oxidative polymerization, leading to the formation of branched, high-molecular-weight polymers with an average of 3.5 or more hydroxyl groups per molecule, ultimately generating gel components insoluble in water-soluble organic solvents.

[0044] On the other hand, if the phenol represented by formula (2) has a bulky substituent at one ortho position, it becomes possible to control the bonding position of the phenol compound during oxidative polymerization, even though it has a hydrogen atom at the opposite ortho position.

[0045] Furthermore, if the phenol represented by formula (2) has a bulky substituent at one of its ortho positions, gelation will not occur even if a monovalent phenol having a non-bulky substituent (e.g., hydrogen atom, allyl group, methyl group, ethyl group, methoxy group, etc.) at the ortho position of the oxygen atom of the phenol is used as the third component.

[0046] Furthermore, the molecular weight of the polyphenylene ether can be adjusted, for example, by the molar ratio of the structure of formula (2) to the total of the structures of formula (1) and formula (2), or by the molar ratio of the structure of formula (7) to the total of the structures of formula (1) and formula (7). In other words, if the molar ratio of the structure of formula (2) or formula (7) is high, the molecular weight (reduced viscosity) can be lowered, and if the molar ratio of the structure of formula (2) or formula (7) is low, the molecular weight (reduced viscosity) can be adjusted to be higher.

[0047] In the method for producing polyphenylene ether, an aromatic solvent, which is a good solvent for polyphenylene ether, can be used as the polymerization solvent in the oxidative polymerization step.

[0048] A good solvent for polyphenylene ether is a solvent that can dissolve polyphenylene ether. Examples of such solvents include aromatic hydrocarbons such as benzene, toluene, xylene (including o-, m-, and p- isomers), and ethylbenzene, as well as halogenated hydrocarbons such as chlorobenzene and dichlorobenzene; nitro compounds such as nitrobenzene; and the like.

[0049] As polymerization catalysts, generally known catalyst systems that can be used for the production of polyphenylene ethers can be used. Commonly known catalyst systems consist of a transition metal ion with redox potential and an amine compound that can form a complex with the transition metal ion. Examples include catalyst systems consisting of a copper compound and an amine compound, a manganese compound and an amine compound, a cobalt compound and an amine compound, etc. Since the polymerization reaction proceeds efficiently under slightly alkaline conditions, a small amount of alkali or further amine compounds may be added.

[0050] Furthermore, preferred polymerization catalysts include catalysts comprising a copper compound, a halogen compound, and an amine compound as catalyst components, and more preferably catalysts containing a diamine compound represented by the following formula (10) as the amine compound. (In formula (10), R 14, R 15 , R 16 , R 17 Each of these is independently a hydrogen atom and a linear or branched alkyl group having 1 to 6 carbon atoms, and not all of them are hydrogen atoms at the same time. 18 (This refers to an alkylene group having 2 to 5 carbon atoms, either linear or methyl-branched.)

[0051] Examples of copper compounds used as catalyst components are listed below. Suitable copper compounds include cuprous compounds, cupric compounds, or mixtures thereof. Examples of cupric compounds include cupric chloride, cupric bromide, cupric sulfate, and cupric nitrate. Examples of cuprous compounds include cuprous chloride, cuprous bromide, cuprous sulfate, and cuprous nitrate. Among these, particularly preferred metallic compounds are cuprous chloride, cupric chloride, cuprous bromide, and cupric bromide. These copper salts may also be synthesized at the time of use from oxides (e.g., cuprous oxide), carbonates, hydroxides, and corresponding halogens or acids. A frequently used method is to prepare them by mixing the previously exemplified cuprous oxide with hydrogen halides (or solutions of hydrogen halides).

[0052] Examples of the halogen compounds include hydrogen chloride, hydrogen bromide, hydrogen iodide, sodium chloride, sodium bromide, sodium iodide, potassium chloride, potassium bromide, potassium iodide, tetramethylammonium chloride, tetramethylammonium bromide, tetramethylammonium iodide, tetraethylammonium chloride, tetraethylammonium bromide, and tetraethylammonium iodide. These can also be used as aqueous solutions or solutions using a suitable solvent. These halogen compounds can be used individually or in combination of two or more types. Preferred halogen compounds are aqueous solutions of hydrogen chloride and aqueous solutions of hydrogen bromide.

[0053] The amount of these compounds used is not particularly limited, but it is preferably 2 to 20 times the amount of halogen atoms relative to the molar amount of copper atoms, and the preferred amount of copper atoms to use per 100 moles of phenol compound added to the polymerization reaction is in the range of 0.02 moles to 0.6 moles.

[0054] For example, the diamine compounds of the catalyst component include N,N,N',N'-tetramethylethylenediamine, N,N,N'-trimethylethylenediamine, N,N'-dimethylethylenediamine, N,N-dimethylethylenediamine, N-methylethylenediamine, N,N,N',N'-tetraethylethylenediamine, N,N,N'-triethylethylenediamine, N,N'-diethylethylenediamine, N,N'-diethylethylenediamine, N-ethylethylenediamine, N,N-dimethyl-N'-ethylethylenediamine, N,N'-dimethyl-N-ethylethylenediamine, N-n-propylethylenediamine, N,N'-n-propylethylenediamine, N-i-propylethylenediamine, N- Examples include n-butylethylenediamine, N,N'-n-butylethylenediamine, N-i-butylethylenediamine, N,N'-i-butylethylenediamine, N-t-butylethylenediamine, N,N'-t-butylethylenediamine, N,N,N'-tetramethyl-1,3-diaminopropane, N,N,N'-trimethyl-1,3-diaminopropane, N,N'-dimethyl-1,3-diaminopropane, N,N'-methyl-1,3-diaminopropane, N,N,N',N'-tetramethyl-1,3-diamino-1-methylpropane, N,N,N',N'-tetramethyl-1,3-diamino-2-methylpropane, N,N,N',N'-tetramethyl-1,4-diaminobutane, and N,N,N',N'-tetramethyl-1,5-diaminopentane. For this embodiment, preferred diamine compounds are those in which the alkylene group connecting the two nitrogen atoms has two or three carbon atoms. The amount of these diamine compounds used is not particularly limited, but it is preferably in the range of 0.01 moles to 10 moles per 100 moles of the phenol compound added to the polymerization reaction.

[0055] Furthermore, the polymerization catalyst may contain primary amines and secondary monoamines as constituent components. Examples of secondary monoamines, but not limited to those listed below, include dimethylamine, diethylamine, di-n-propylamine, di-i-propylamine, di-n-butylamine, di-i-butylamine, di-t-butylamine, dipentylamines, dihexylamines, dioctylamines, didecylamines, dibenzylamines, methylethylamine, methylpropylamine, methylbutylamine, cyclohexylamine, N-phenylmethanolamine, N-phenylethanolamine, N-phenylpropanolamine, N-(m-methylphenyl)ethanolamine, N-(p-methylphenyl)ethanolamine, N-(2',6'-dimethylphenyl)ethanolamine, N-(p-chlorophenyl)ethanolamine, N-ethylaniline, N-butylaniline, N-methyl-2-methylaniline, N-methyl-2,6-dimethylaniline, and diphenylamine.

[0056] The polymerization catalyst may also contain a tertiary monoamine compound. A tertiary monoamine compound is an aliphatic tertiary amine, including alicyclic tertiary amines. Examples include trimethylamine, triethylamine, tripropylamine, tributylamine, triisobutylamine, dimethylethylamine, dimethylpropylamine, allyldiethylamine, dimethyl-n-butylamine, diethylisopropylamine, and N-methylcyclohexylamine. These tertiary monoamines may be used individually or in combination of two or more. The amount used is not particularly limited, but it is preferably in the range of 15 moles or less per 100 moles of the phenol compound added to the polymerization reaction.

[0057] In this embodiment, there are no restrictions on adding surfactants that are conventionally known to have an effect of improving polymerization activity. Examples of such surfactants include trioctylmethylammonium chloride, known by the trade names Aliquat 336 and Capriquat.

[0058] As the oxygen-containing gas used in the polymerization, pure oxygen, a mixture of oxygen and an inert gas such as nitrogen in any proportion, air, or a mixture of air and an inert gas such as nitrogen in any proportion can be used. While atmospheric pressure is sufficient for the system pressure during the polymerization reaction, it can be reduced or increased as needed.

[0059] The polymerization temperature is not particularly limited, but if it is too low, the reaction will not proceed easily, and if it is too high, the reaction selectivity may decrease or a gel may form. Therefore, it is in the range of 0 to 60°C, preferably 10 to 40°C.

[0060] In the method for producing polyphenylene ether, polymerization can also be carried out in a poor solvent such as alcohol.

[0061] Furthermore, there are no particular restrictions on the post-treatment method after the polymerization reaction is completed in the method for producing polyphenylene ether. Typically, an acid such as hydrochloric acid or acetic acid, or ethylenediaminetetraacetic acid (EDTA) and its salts, nitrilotriacetic acid and its salts, etc., are added to the reaction solution to deactivate the catalyst. In addition, the removal of divalent phenol by-products generated by the polymerization of polyphenylene ether can also be carried out using conventionally known methods. If the metal ions that act as catalysts are substantially deactivated as described above, the mixture can be decolorized simply by heating it. Alternatively, it is also possible to add the required amount of a known reducing agent. Examples of known reducing agents include hydroquinone and sodium dithionite.

[0062] In a method for producing polyphenylene ether, water may be added to extract the compound from which the copper catalyst has been deactivated, followed by liquid-liquid separation into an organic phase and an aqueous phase. The copper catalyst may then be removed from the organic phase by removing the aqueous phase. This liquid-liquid separation step is not particularly limited, but examples include static separation and separation by centrifugation. To promote the above liquid-liquid separation, known surfactants may be used.

[0063] ・Precipitation step Subsequently, in the method for producing polyphenylene ether of this embodiment, the target polyphenylene ether can be isolated by adding the organic phase containing the polyphenylene ether after liquid-liquid separation to a poor solvent for the polyphenylene ether to precipitate the polyphenylene ether. The poor solvent is at least one selected from the group consisting of methanol, ethanol, isopropanol, n-butanol, acetone, methyl ethyl ketone, and N-methyl-2-pyrrolidone. Furthermore, from the viewpoint of removing low molecular weight components of the polyphenylene ether, it is preferable that the poor solvent contains a first solvent and a second solvent.

[0064] The first solvent is preferably an alcohol having 1 to 3 carbon atoms, and more preferably methanol. The second solvent is preferably an alcohol, ketone, amide, or lactome having 4 to 8 carbon atoms, more preferably an alcohol, acetone, methyl ethyl ketone, or N-methyl-2-pyrrolidone, particularly preferably butanol or methyl ethyl ketone, and most preferably methyl ethyl ketone.

[0065] The solubility parameter (SP value) of the second solvent (unit: cal / cm³) ３ ) １／２ From the viewpoint of being able to dissolve and remove low molecular weight components, the solubility parameter is preferably 9.0 to 12.0. From the same viewpoint, it is more preferably 9.0 to 11.5, particularly preferably 9.0 to 11.0, and most preferably 9.0 to 10.0. Here, the solubility parameter is the solubility parameter (unit (cal / cm³)) calculated by the Fedors method described in Polymer Handbook Third Edition (A Wiley-Interscience Publication, 1989). ３ ) １／２) is shown. The atmospheric pressure boiling point of the second solvent is preferably 200°C or lower from the viewpoint of ease of removal by drying. From the same viewpoint, it is more preferably 160°C or lower, particularly preferably 140°C or lower, and most preferably 100°C or lower. The mass ratio of the first solvent to the second solvent is preferably 1:99 to 99:1 from the viewpoint of efficiently removing low molecular weight components. When the mass ratio of the second solvent is 1% or more, the removal of low molecular weight components is effectively achieved, and when the mass ratio of the first solvent is 1% or more, the non-coagulation of the precipitated polymer is excellent. From the same viewpoint, it is more preferably 5:95 to 80:20, particularly preferably 10:90 to 70:30, and most preferably 10:90 to 49:51.

[0066] The drying temperature in the drying process described above is preferably at least 60°C, more preferably 80°C or higher, even more preferably 120°C or higher, and most preferably 140°C or higher. Drying the polyphenylene ether at a temperature of 60°C or higher efficiently reduces the content of high-boiling point volatile components in the polyphenylene ether powder.

[0067] To obtain the aforementioned polyphenylene ether with high efficiency, methods such as increasing the drying temperature, increasing the vacuum level in the drying atmosphere, and stirring during drying are effective, but increasing the drying temperature is particularly preferred from the viewpoint of manufacturing efficiency. In the drying process, it is preferable to use a dryer equipped with a mixing function. Examples of mixing functions include agitation type and tumbling type dryers. This allows for a larger processing volume and maintains high productivity.

[0068] (Porous membrane) The porous membrane of this embodiment is obtained from the polyphenylene ether of this embodiment described above. The form of the porous membrane in this embodiment is not particularly limited, but typical examples include flat membranes and hollow fiber membranes. By fabricating a porous membrane from the polyphenylene ether of this embodiment, a porous membrane with high mechanical properties can be obtained.

[0069] Furthermore, the porous membrane of this embodiment can be manufactured, for example, by a non-solvent-induced phase separation method. This is a typical method for manufacturing porous membranes, in which a porous membrane is produced by immersing a homogeneous polymer solution in a non-solvent. The non-solvent-induced phase separation method in this invention may include, for example, the steps of preparing a polyphenylene ether solution, adjusting the temperature of the polyphenylene ether solution, forming a film on a substrate by coating, solidification, immersing the substrate and the film in a solidification solution, and removing the film from the solidification solution and drying it under appropriate conditions. An example of the non-solvent-induced phase separation method in this embodiment is the method described in Polymers 2023, 15(21), 4307, Andrey Basko, "Mechanism of PVDF Membrane Formation by NIPS Revisited: Effect of Precipitation Bath Nature and Polymer-Solvent Affinity". It is preferable that the porous membrane of this embodiment can be manufactured at room temperature (20°C). The polyphenylene ether of this embodiment has high solubility in water-soluble organic solvents, and a uniform polyphenylene ether solution can be prepared even at room temperature, thus enabling the formation of porous films at room temperature. By adopting the above configuration, the handling and safety of the solution during film production are improved.

[0070] The porous membrane of this embodiment can be used for any liquid separation application targeting size separation. Particularly suitable applications include filters used in medical, pharmaceutical, and food and beverage applications, as well as related applications, water electrolysis applications, and water treatment applications. Specifically, these include various filters used in medical applications such as plasma filtration, virus removal, and various blood purification applications including hemodialysis; various process filters used in pharmaceutical applications such as the purification process of synthetic pharmaceuticals such as anticancer agents and antibiotics, the purification process of highly purified amino acids for pharmaceutical use, and the purification process of antibody drugs such as polyclonal antibodies and monoclonal antibodies; and various process filters used in food applications such as filters used in the production of various beverages such as sake, beer, wine, sparkling wine, tea, oolong tea, vegetable juice, and fruit juice. In particular, it can also be used as a process filter for the purpose of removing aggregates of immunoglobulins, which are antibody drugs. Furthermore, blood treatment applications in this invention refer to blood treatment applications such as blood purification, and include plasma filtration filters, virus removal filters, and hollow fiber filters for hemodialysis, which are included in the medical applications mentioned above. A specific example of a water electrolysis application is a diaphragm used to prevent the mixing of gases generated in the water electrolyte. Specific examples of its use in water treatment include water purification, process water production, sewage treatment, industrial wastewater treatment, and seawater desalination.

[0071] The porous membrane of this embodiment is particularly preferably used for alkaline water electrolysis, pharmaceutical process filters, and water treatment.

[0072] In this embodiment, a porous membrane is a membrane used for separating solids, liquids, and gases from a mixed liquid that is liquid at the temperature at which the separation process is performed. However, membranes whose separation principle is dissolution / diffusion of the substances to be separated into the membrane rather than size are not included in the category of porous membranes in this embodiment.

[0073] (Diaphragm for Alkaline Water Electrolysis) The diaphragm for alkaline water electrolysis in this embodiment consists of the porous membrane of this embodiment. By using the porous membrane of this embodiment, an alkaline water electrolysis diaphragm that can withstand use without rupturing even when exposed to strong water flow or pressure can be obtained.

[0074] (Pharmaceutical Process Filter) The pharmaceutical process filter of this embodiment consists of the porous membrane of this embodiment. By using the porous membrane of this embodiment, a pharmaceutical process filter that can withstand use without rupturing even when exposed to strong water flow or pressure can be obtained.

[0075] (Water Treatment Membrane) The water treatment membrane of this embodiment consists of the porous membrane of this embodiment. By using the porous membrane of this embodiment, a water treatment membrane that can withstand use without rupturing even when exposed to strong water flow or pressure can be obtained.

[0076] The embodiments of this invention will be described in more detail below based on examples, but the embodiments of the present invention are not limited to the following examples.

[0077] (Production of polyphenylene ether) ・Example 1: Polyphenylene ether 1 (PPE1) A 1 L jacketed polymerization tank equipped with a sparger, stirring turbine blades and baffles for introducing oxygen-containing gas at the bottom of the polymerization tank, and a reflux condenser in the vent gas line at the top of the polymerization tank, was subjected to nitrogen gas injection at a flow rate of 1.39 L / min while adding 0.112 g of cupric oxide, 0.843 g of 47% by mass aqueous solution of hydrogen bromide, 0.270 g of di-tert-butylethylenediamine, 1.316 g of di-n-butylamine, 3.963 g of butyldimethylamine, and 0.06 g of trioctylmethylammonium chloride (R=C ８ -C １０11.70 g of 2-tert-butyl-5-methylphenol, 78.30 g of 2,6-dimethylphenol, and 503.4 g of toluene were added to prepare a homogeneous polymerization solution. Dry air was introduced into the polymerization solution from a sparger at a rate of 0.95 L / min to start polymerization. Dry air was passed through for 240 minutes to obtain the polymerization mixture. The internal temperature was controlled to 40°C during polymerization. At the end of polymerization, the polymerization mixture (polymerization solution) was in a homogeneous solution state. Subsequently, the flow of dry air was stopped, and 1.208 g of tetrasodium ethylenediaminetetraacetate (reagent manufactured by Dojin Chemical Laboratories) was added to the polymerization mixture as an aqueous solution in a volume of 61.208 g. The polymerization mixture was stirred at 70°C for 360 minutes, then allowed to stand for 240 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The above organic phase was diluted to 10% by mass. The diluted solution described above was mixed with a poor solvent four times the mass of the polymer solution, and polymer precipitation was carried out. The poor solvent used was methyl ethyl ketone (SP value: 9.3 (cal / cm³)). ３ ) １／２ ) and methanol (SP value: 14.5 (cal / cm³) ３ ) １／２ A mixed solvent with a mass ratio of 70:30 was used. Wet polyphenylene ether was obtained by vacuum filtration using a glass filter. The wet polyphenylene ether was then washed with methanol at a volume four times its mass, and this washing operation was repeated three times. After that, the wet polyphenylene ether was maintained at 140°C and 1 mmHg for 120 minutes to obtain dry polyphenylene ether-1 (PPE1).

[0078] Example 2: Polyphenylene ether 2 (PPE2) The procedure was carried out in the same manner as in Example 1, except that a mixed solvent of methyl ethyl ketone and methanol in a mass ratio of 60:40 was used as the poor solvent during precipitation, to obtain polyphenylene ether 2 (PPE2).

[0079] Example 3: Polyphenylene ether 3 (PPE3) The procedure was carried out in the same manner as in Example 1, except that the drying time for the dry air during polymerization was 210 minutes, to obtain dry polyphenylene ether-3 (PPE3).

[0080] Example 4: Polyphenylene ether 4 (PPE4) The procedure was carried out in the same manner as in Example 3, except that the phenol raw materials were 84.05 g of 2,6-dimethylphenol and 5.95 g of 2-tert-butyl-5-methylphenol, to obtain dry polyphenylene ether 4 (PPE4).

[0081] Example 5: Polyphenylene ether 5 (PPE5) The procedure was carried out in the same manner as in Example 3, except that the phenol raw materials were 72.74 g of 2,6-dimethylphenol and 17.26 g of 2-tert-butyl-5-methylphenol, to obtain dry polyphenylene ether 5 (PPE5).

[0082] Example 6: Polyphenylene ether 6 (PPE6) n-butanol (SP value: 11.4 (cal / cm³)) was used as the poor solvent during precipitation. ３ ) １／２ The procedure was carried out in the same manner as in Example 3, except that a mixed solvent of ) and methanol in a ratio of 70:30 was used to obtain polyphenylene ether 6 (PPE6).

[0083] Example 7: Polyphenylene ether 7 (PPE7) The procedure was carried out in the same manner as in Example 3, except that the phenol raw materials were 57.10 g of 2,6-dimethylphenol and 32.90 g of 2-tert-butyl-5-methylphenol, to obtain dry polyphenylene ether 7 (PPE7).

[0084] Comparative Example 1: Polyphenylene ether 8 (PPE8) Polyphenylene ether 8 (PPE8) was obtained by following the same procedure as in Example 1, except that methanol was used as the poor solvent during precipitation.

[0085] Comparative Example 2: Polyphenylene ether 9 (PPE9) Polyphenylene ether 9 (PPE9) was obtained by following the same procedure as in Example 3, except that methanol was used as the poor solvent during precipitation.

[0086] Comparative Example 3: Polyphenylene ether 10 (PPE10) Polyphenylene ether 10 (PPE10) was obtained by following the same procedure as in Example 5, except that methanol was used as the poor solvent during precipitation.

[0087] Comparative Example 4: Polyphenylene Ether 11 (PPE11) Polyphenylene ether was obtained as described below according to the method described in Example 4 of Japanese Patent Publication No. 56-104935. A jacketed polymerization tank of type L, equipped with a sparger for introducing oxygen-containing gas at the bottom of the polymerization tank, stirring turbine blades and baffles, and a reflux condenser in the vent gas line at the top of the polymerization tank, was filled with 1.0 g of dehydrated manganese chloride, 4.8 g of ethylenediamine, 6.57 g of 2-tert-butyl-5-methylphenol, 43.98 g of 2,6-dimethylphenol, 195.0 g of xylene, and 84.0 g of methanol to make a homogeneous polymerization solution. Oxygen gas was introduced into the polymerization solution from the sparger at a rate of 0.50 L / min to start polymerization. Oxygen gas was passed through for 360 minutes to obtain a polymerization mixture. The internal temperature was controlled to 30°C during polymerization. Subsequently, the supply of oxygen gas was stopped, and 17 mL of concentrated hydrochloric acid was added to the polymerization mixture. The polymerization mixture was stirred at 60°C for 60 minutes, then allowed to stand for 240 minutes, and the organic phase and aqueous phase were separated by liquid-liquid separation. The organic phase was diluted to 10% by mass. The diluted solution was mixed with a poor solvent four times the mass of the polymer solution, and the polymer was precipitated. Methanol was used as the poor solvent. Wet polyphenylene ether was obtained by vacuum filtration using a glass filter. The wet polyphenylene ether was then washed with methanol four times the mass of the wet polyphenylene ether, and this washing operation was repeated three times. After that, the wet polyphenylene ether was held at 140°C and 1 mmHg for 120 minutes to obtain dry polyphenylene ether-11 (PPE11).

[0088] Comparative Example 5: Polyphenylene ether 12 (PPE12) Polyphenylene ether 12 (PPE12) was obtained by following the same procedure as in Example 1, except that 90.0 g of 2,6-dimethylphenol was used as the phenol raw material and the drying time with dry air during polymerization was 130 minutes.

[0089] Comparative Example 6: Polyphenylene ether 13 (PPE13) Polyphenylene ether 13 (PPE13) was obtained by following the same procedure as in Comparative Example 12, except that methanol was used as the poor solvent during precipitation.

[0090] (Number-average molecular weight (Mn) and molecular weight distribution (Mw / Mn) of polyphenylene ethers) A gel permeation chromatography system (Shimadzu Corporation, LC-2030C Plus) was used as the measuring instrument. A calibration curve was created using standard polystyrene and ethylbenzene, and the number-average molecular weight (Mn) of the obtained polyphenylene ethers was measured using this calibration curve. Standard polystyrenes with molecular weights of 3,650,000, 2,170,000, 1,090,000, 681,000, 204,000, 52,000, 30,200, 13,800, 3,360, 1,300, and 550 were used. Two K-805L columns manufactured by Showa Denko K.K. were connected in series. Chloroform was used as the solvent, with a solvent flow rate of 1.0 mL / min and a column temperature of 40°C. For measurement, a 1 g / L chloroform solution of polyphenylene ether was prepared and used as the sample. The UV wavelength of the detection unit was set to 254 nm for standard polystyrene and 283 nm for polyphenylene ether. Based on the above measurement data, the number-average molecular weight (Mn) (g / mol), weight-average molecular weight (Mw), and molecular weight distribution (Mw / Mn) were calculated from the ratio of peak areas based on the molecular weight distribution curve obtained by GPC. Also, the molecular weight was calculated as 1.0 × 10⁻⁶. ４ The following polyphenylene ether component ratios and molecular weights are 5.0 × 10 ３ The following polyphenylene ether component ratios are calculated from the ratio of areas below each molecular weight, with the total area enclosed by the differential molecular weight distribution curve obtained by GPC set to 100%.

[0091] (Preparation and Evaluation of Polyphenylene Ether Porous Membranes) The obtained polyphenylene ethers (PPE1-13) and the water-soluble organic solvent N-methyl-2-pyrrolidone (NMP) (manufactured by Hayashi Pure Chemical Industries, Ltd.) were mixed in a ratio of 20:80 to polyphenylene ether to NMP to prepare a polyphenylene ether solution. The following evaluations were then performed.

[0092] (1) Film-forming properties at room temperature A polyphenylene ether solution, which has been left standing at room temperature (20°C), was gently dropped onto a glass plate that had been left standing at room temperature (20°C). The solution was spread evenly using an applicator (wet thickness setting: 150 μm) and quickly immersed in a solidification solution (pure water) kept warm at 80°C. At this stage, the film-forming properties were evaluated according to the following criteria. The evaluation results are shown in Table 1. Good: A uniform and transparent solution was obtained, the uniformity of the polymer film was maintained even after coating, and it was easy to form a uniform film. Poor: The polymer solution at room temperature was non-uniform, making it difficult to form a uniform film.

[0093] Next, the following evaluations were performed on the obtained porous membrane. (2) Bending test The bending test of the porous membrane was performed five times under an atmosphere of 25°C and 65% RH, bending the membrane 180° at a bending radius of 1 mm. The condition in which no cracks occurred was evaluated as "○", the condition in which cracks occurred from the 2nd to the 5th time was evaluated as "△", and the condition in which cracks occurred on the 1st time was evaluated as "×".

[0094]

[0095] Table 1 shows that for Examples 1 to 7, the fabricated porous films exhibited excellent mechanical properties and yielded good results in bending tests. Examples 1 to 4 showed particularly outstanding properties. On the other hand, for Comparative Examples 1 to 4, the mechanical properties were found to be inferior to those of the examples. For Comparative Examples 5 to 6, the low solubility of polyphenylene ether in water-soluble organic solvents made it impossible to fabricate porous films at room temperature.

[0096] According to the present invention, it is possible to provide a polyphenylene ether with a low molecular weight component ratio and excellent solubility in water-soluble organic solvents, and a method for producing the same. Furthermore, according to the present invention, it is possible to provide a porous membrane with improved mechanical properties made using the above polyphenylene ether, and a diaphragm for alkaline electrolysis, a process filter for pharmaceuticals, and a water treatment membrane using such a porous membrane.

Claims

1. With respect to a total of 100 mol% of the repeating units of the following formula (1) and the following formula (2), the content of the repeating unit derived from phenol of the following formula (1) is 70 mol% or more and 99.5 mol% or less, and the content of the repeating unit derived from phenol of the following formula (2) is 0.5 mol% or more and 30 mol% or less. The polyphenylene ether is characterized in that the following polyphenylene ether component is 15% by weight or less. 32 , 31 , 31 , 33 The polyphenylene ether is characterized in that the following polyphenylene ether component is 15% by weight or less. (In formula (1), R 11 is each independently an optionally substituted saturated hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom, and R 12 is each independently a hydrogen atom, an optionally substituted hydrocarbon group having 1 to 6 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom.) (In formula (2), R 22 is each independently a hydrogen atom, an optionally substituted saturated or unsaturated hydrocarbon group having 1 to 20 carbon atoms, an optionally substituted aryl group having 6 to 12 carbon atoms, or a halogen atom. Two R 22 are not both hydrogen atoms, and R 21 is a partial structure represented by the following formula (3). (In formula (3), R 31 is each independently an optionally substituted linear alkyl group having 1 to 8 carbon atoms, or a cyclic alkyl structure having 1 to 8 carbon atoms to which two R 31 are bonded. R 32 is each independently an optionally substituted alkylene group having 1 to 8 carbon atoms. b is each independently 0 or 1. R 33 is a hydrogen atom, an optionally substituted alkyl group having 1 to 8 carbon atoms, or an optionally substituted phenyl group.)) 2. The polyphenylene ether according to claim 1, characterized in that the substructure represented by formula (3) is a t-butyl group.

3. The weight-average molecular weight (Mw) determined by gel permeation chromatography (GPC) is 7.0 × 10⁻⁶. ４ The polyphenylene ether according to claim 1, characterized in that it is as described above.

4. The polyphenylene ether according to claim 1, characterized in that the molecular weight distribution (Mw / Mn) determined by gel permeation chromatography (GPC) is 2.0 to 5.

0.

5. Molecular weight determined by gel permeation chromatography (GPC): 5.0 × 10⁻⁶ ３ The polyphenylene ether according to claim 1, characterized in that the following polyphenylene ether components are present in an amount of 8.0% by weight or less.

6. Molecular weight 5.0 × 10⁻¹⁶ as determined by gel permeation chromatography (GPC). ５ The polyphenylene ether according to claim 1, characterized in that the above polyphenylene ether components are 20% by weight or less.

7. A method for producing polyphenylene ether according to any one of claims 1 to 6, comprising: a polymerization step of polymerizing a phenol compound to obtain a crude polymer; and a precipitation step of mixing the crude polymer with a precipitation solvent to precipitate polyphenylene ether, wherein the precipitation solvent comprises a first solvent and a second solvent, and the solubility parameter (SP value) of the second solvent (unit (cal / cm)) ３ ) １／２ A method for producing polyphenylene ether, characterized in that the ratio is 9.0 or more and 12.0 or less.

8. The method for producing a polyphenylene ether according to claim 7, characterized in that the first solvent is an alcohol having 1 to 3 carbon atoms.

9. The method for producing a polyphenylene ether according to claim 7, characterized in that the second solvent is an alcohol, ketone, ester, amide, or lactome having 4 to 8 carbon atoms.

10. The method for producing polyphenylene ether according to claim 7, characterized in that the second solvent is an alcohol having 4 to 8 carbon atoms, acetone, methyl ethyl ketone, or N-methyl-2-pyrrolidone.

11. The method for producing polyphenylene ether according to claim 7, characterized in that the mass ratio of the first solvent to the second solvent is 10:90 to 49:

51.

12. The method for producing polyphenylene ether according to claim 7, characterized in that the first solvent is methanol and the second solvent is methyl ethyl ketone.

13. A porous membrane characterized by comprising a polyphenylene ether according to any one of claims 1 to 6.

14. A pharmaceutical process filter characterized by comprising the porous membrane described in claim 13.

15. A water treatment membrane characterized by comprising the porous membrane described in claim 13.

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